How to increase FPS in Dota 2 .
Step 1 : Overclock your GPU and download GAME BOOSTER. Close all unescesarry programs.
Step 2 : Off your themes and set it to best performance.
Step 3: While in Dota 2 go to settings>video> TURN OFF Vsync and especially ANTI-ALIASING and turn all effects to low except ANIMATE PORTRAIT .

I have my HD 5450 and running at 50-60 FPS in 1360x768 resolution . Quality and Performance. )

1. Overclocking GPU is NOT for regular people.
2. Gamebooster is actually SLOWING YOU DOWN if you have no idea what it does. A simple "exit program" is enough.
3. Actually, playing at 1360x768 resolution is very intensive for bad PCs. Lowering to 800x600 will DRAMATICALLY increase your FPS.